package com.wyc.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import org.springframework.cglib.core.internal.Function;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;


import static com.wyc.utils.RedisConstants.*;

@Component
public class CacheCline {
    private final StringRedisTemplate stringRedisTemplate;

    public CacheCline(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        // 设置逻辑过期
        RedisData rd = new RedisData();
        rd.setData(value);
        rd.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        // 写入Redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(rd));
    }

    public <R, ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback,
            Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        // 从redis获取缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        // 判断是否存在
        if (StrUtil.isNotBlank(json)) {
            // 存在，直接返回
            return JSONUtil.toBean(json, type);
        }
        // 判断命中的是否是空值
        if (json != null) {
            // 返回一个错误信息
            return null;
        }
        // 不存在，根据id查询数据库
        R r = dbFallback.apply(id);
        // 不存在，返回错误
        if (r == null) {
            // 将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", time, unit);
            // 返回错误信息
            return null;
        }
        // 存在，写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(r), time, unit);
        return r;
    }

    // 线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public <R, ID> R queryWithLogicalExpire(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback,
                                          Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        // 从redis获取缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        // 如果存在直接返回
        if (StrUtil.isBlank(json)) {
            return null;
        }
        // 命中,把JSON反序列化为对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        // 先把数据转为JSONObject
        JSONObject data = JSONUtil.parseObj(redisData.getData());
        // 再转为具体对象
        R r = JSONUtil.toBean(data, type);
        LocalDateTime expireTime = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now())) {
            // 未过期 直接返回店铺信息
            return r;
        }
        //  过期了

        String lockKey = LOCK_SHOP_KEY + id;
        Boolean isLock = tryLock(lockKey);
        // 判断是否成功获取锁
        if (isLock) {
            // 成功, 开启独立线程，实现缓存重写
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    // 查询数据库
                    R r1 = dbFallback.apply(id);
                    // 写入Redis
                    this.setWithLogicalExpire(key, r1, time, unit);
        
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    // 释放锁
                    unlock(lockKey);
                }
            });
        }
       
        return r;
    }

    private boolean tryLock(String Key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(Key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String Key) {
        stringRedisTemplate.delete(Key);
    }
}
